Use unique_xmalloc_ptr in Python code

This changes some utility functions in the Python code to return
unique_xmalloc_ptr, and then fixes up the callers.

I chose unique_xmalloc_ptr rather than std::string because at a few
call points the xmalloc'd string is released and ownership transferred
elsewhere.

This patch found a few existing memory leaks.  For example,
py-unwind.c called gdbpy_obj_to_string but never freed the result.

Built and regression tested on the buildbot.

2016-11-09  Tom Tromey  <tom@tromey.com>

	* varobj.h (varobj_get_display_hint): Change return type.
	* varobj.c (varobj_get_display_hint): Return unique_xmalloc_ptr.
	(varobj_value_get_print_value): Update.
	* python/python.c (gdbpy_before_prompt_hook, gdbpy_print_stack)
	(gdbpy_apply_type_printers): Update.
	* python/python-internal.h (unicode_to_target_string)
	(python_string_to_target_string, python_string_to_host_string)
	(gdbpy_obj_to_string, gdbpy_exception_to_string)
	(gdbpy_get_display_hint): Change return types.
	* python/py-varobj.c (py_varobj_iter_next): Update.
	* python/py-value.c (valpy_getitem, convert_value_from_python):
	Update.
	* python/py-utils.c (unicode_to_encoded_string)
	(unicode_to_target_string, python_string_to_target_string)
	(python_string_to_host_string, gdbpy_obj_to_string)
	(gdbpy_exception_to_string): Return unique_xmalloc_ptr.
	* python/py-unwind.c (pyuw_parse_register_id): Update.
	* python/py-type.c (typy_getitem): Update.
	* python/py-prettyprint.c (gdbpy_get_display_hint)
	(print_stack_unless_memory_error, print_children)
	(gdbpy_apply_val_pretty_printer): Update.
	* python/py-param.c (set_parameter_value): Update.
	(get_doc_string, call_doc_function): Return unique_xmalloc_ptr.
	(get_set_value, get_show_value, compute_enum_values, parmpy_init):
	Update.
	* python/py-infthread.c (thpy_set_name): Update.
	* python/py-function.c (fnpy_call, fnpy_init): Update.
	* python/py-framefilter.c (extract_sym): Change "name" to
	unique_xmalloc_ptr.
	(enumerate_args, enumerate_locals): Update.
	(py_print_frame): Use unique_xmalloc_ptr.
	* python/py-frame.c (frapy_read_var): Update.  Remove cleanup.
	* python/py-cmd.c (cmdpy_function, cmdpy_completer, cmdpy_init):
	Update.
	* python/py-breakpoint.c (bppy_set_condition): Use
	unique_xmalloc_ptr.
	(bppy_init): Likewise.  Remove cleanup.
	(local_setattro): Update.
	* mi/mi-cmd-var.c (print_varobj, mi_cmd_var_list_children)
	(varobj_update_one): Update.

1 files changed, 12 insertions, 12 deletions

diff --git a/gdb/python/python.c b/gdb/python/python.c
index d9940c2..321479b 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1020,7 +1020,7 @@ gdbpy_before_prompt_hook (const struct extension_language_defn *extlang,
 			  const char *current_gdb_prompt)
 {
   struct cleanup *cleanup;
-  char *prompt = NULL;
+  gdb::unique_xmalloc_ptr<char> prompt;
 
   if (!gdb_python_initialized)
     return EXT_LANG_RC_NOP;
@@ -1073,8 +1073,6 @@ gdbpy_before_prompt_hook (const struct extension_language_defn *extlang,
 
 	      if (prompt == NULL)
 		goto fail;
-	      else
-		make_cleanup (xfree, prompt);
 	    }
 	}
     }
@@ -1082,7 +1080,7 @@ gdbpy_before_prompt_hook (const struct extension_language_defn *extlang,
   /* If a prompt has been set, PROMPT will not be NULL.  If it is
      NULL, do not set the prompt.  */
   if (prompt != NULL)
-    set_prompt (prompt);
+    set_prompt (prompt.get ());
 
   do_cleanups (cleanup);
   return prompt != NULL ? EXT_LANG_RC_OK : EXT_LANG_RC_NOP;
@@ -1213,13 +1211,13 @@ gdbpy_print_stack (void)
   else
     {
       PyObject *ptype, *pvalue, *ptraceback;
-      char *msg = NULL, *type = NULL;
 
       PyErr_Fetch (&ptype, &pvalue, &ptraceback);
 
       /* Fetch the error message contained within ptype, pvalue.  */
-      msg = gdbpy_exception_to_string (ptype, pvalue);
-      type = gdbpy_obj_to_string (ptype);
+      gdb::unique_xmalloc_ptr<char>
+	msg (gdbpy_exception_to_string (ptype, pvalue));
+      gdb::unique_xmalloc_ptr<char> type (gdbpy_obj_to_string (ptype));
 
       TRY
 	{
@@ -1233,7 +1231,7 @@ gdbpy_print_stack (void)
 	    }
 	  else
 	    fprintf_filtered (gdb_stderr, "Python Exception %s %s: \n",
-			      type, msg);
+			      type.get (), msg.get ());
 	}
       CATCH (except, RETURN_MASK_ALL)
 	{
@@ -1243,7 +1241,6 @@ gdbpy_print_stack (void)
       Py_XDECREF (ptype);
       Py_XDECREF (pvalue);
       Py_XDECREF (ptraceback);
-      xfree (msg);
     }
 }
 
@@ -1448,7 +1445,7 @@ gdbpy_apply_type_printers (const struct extension_language_defn *extlang,
   PyObject *type_obj, *type_module = NULL, *func = NULL;
   PyObject *result_obj = NULL;
   PyObject *printers_obj = (PyObject *) ext_printers->py_type_printers;
-  char *result = NULL;
+  gdb::unique_xmalloc_ptr<char> result;
 
   if (printers_obj == NULL)
     return EXT_LANG_RC_NOP;
@@ -1501,8 +1498,11 @@ gdbpy_apply_type_printers (const struct extension_language_defn *extlang,
   Py_XDECREF (result_obj);
   do_cleanups (cleanups);
   if (result != NULL)
-    *prettied_type = result;
-  return result != NULL ? EXT_LANG_RC_OK : EXT_LANG_RC_ERROR;
+    {
+      *prettied_type = result.release ();
+      return EXT_LANG_RC_OK;
+    }
+  return EXT_LANG_RC_ERROR;
 }
 
 /* Free the result of start_type_printers.